Considering lighting system performance and HVAC interactions in lighting retrofit analyses

The performance of several typical fluorescent lighting retrofits are examined, using analysis methods of varying sophistication. It is seen that estimates of energy and lighting performance based on the simple nonapplication-specific data generally available tend to overestimate the energy savings obtained with the various retrofits by 10-30%. Adding a simple correction to account for cooling benefits exacerbates the error unless heating penalties are also considered. An analysis that takes into account the thermal application factor of the lighting system shows that the error is typically due to systematically overestimating the energy usage of the original lighting system. If the thermal application factor is considered, then detailed HVAC calculations do not significantly improve the energy savings estimate